Diabetes is a group of diseases characterized by high levels of blood glucose resulting from the inability of diabetic patients to maintain proper levels of insulin production when required. Diabetes can be dangerous to the affected patient if it is not treated, and it can lead to serious health complications and premature death. However, such complications can be minimized by utilizing one or more treatment options to help control the diabetes and reduce the risk of complications.
The treatment options for diabetic patients include specialized diets, oral medications and/or insulin therapy. The main goal of diabetes treatment is to control the diabetic patient's blood glucose or sugar level. However, maintaining proper diabetes management may be complicated because it has to be balanced with the activities of the diabetic patient. Type 1 diabetes (T1D) patients are required to take insulin (e.g., via injections or infusion) to move glucose from the bloodstream because their bodies generally cannot produce insulin. Type 2 diabetes (T2D) patients generally can produce insulin but their bodies cannot use the insulin properly to maintain blood glucose levels within medically acceptable ranges. In contrast to people with T1D, the majority of those with T2D usually do not require daily doses of insulin to survive. Many people are able to manage their condition through a healthy diet and increased physical activity or oral medication. However, if they are unable to regulate their blood glucose levels, they will be prescribed insulin. For example, there are an estimated 6.2 million Type 2 diabetes patients (e.g., in the United States, Western Europe and Canada) taking multiple-daily-injections (MDI) which consist of a 24-hour basal insulin and a short acting rapid insulin that is taken at mealtimes for glycemic management control.
For the treatment of Type 1 diabetes (T1D) and sometimes Type 2 diabetes (T2D), there are two principal methods of daily insulin therapy. In the first method, diabetic patients use syringes or insulin pens to self-inject insulin when needed. This method requires a needle stick for each injection, and the diabetic patient may require three to four injections daily. The syringes and insulin pens that are used to inject insulin are relatively simple to use and cost effective.
Another effective method for insulin therapy and managing diabetes is infusion therapy or infusion pump therapy in which an insulin pump is used. The insulin pump can provide continuous infusion of insulin to a diabetic patient at varying rates to more closely match the functions and behavior of a properly operating pancreas of a non-diabetic person that produces the required insulin, and the insulin pump can help the diabetic patient maintain his/her blood glucose level within target ranges based on the diabetic patient's individual needs. Infusion pump therapy requires an infusion cannula, typically in the form of an infusion needle or a flexible catheter, that pierces the diabetic patient's skin and through which infusion of insulin takes place. Infusion pump therapy offers the advantages of continuous infusion of insulin, precision dosing, and programmable delivery schedules.
In infusion therapy, insulin doses are typically administered at a basal rate and in a bolus dose. When insulin is administered at a basal rate, insulin is delivered continuously over 24 hours to maintain the diabetic patient's blood glucose levels in a consistent range between meals and rest, typically at nighttime. Insulin pumps may also be capable of programming the basal rate of insulin to vary according to the different times of the day and night. In contrast, a bolus dose is typically administered when a diabetic patient consumes a meal, and generally provides a single additional insulin injection to balance the consumed carbohydrates. Insulin pumps may be configured to enable the diabetic patient to program the volume of the bolus dose in accordance with the size or type of the meal that is consumed by the diabetic patient. In addition, insulin pumps may also be configured to enable the diabetic patient to infuse a correctional or supplemental bolus dose of insulin to compensate for a low blood glucose level at the time when the diabetic patient is calculating the bolus dose for a particular meal that is to be consumed.
Insulin pumps advantageously deliver insulin over time rather than in single injections, typically resulting in less variation within the blood glucose range that is recommended. In addition, insulin pumps may reduce the number of needle sticks which the diabetic patient must endure, and improve diabetes management to enhance the diabetic patient's quality of life. For example, many of the T2D patients who are prescribed insulin therapy can be expected to convert from injections to infusion therapy due to an unmet clinical need for improved control. That is, a significant number of the T2D patients who take multiple-daily-injections (MDI) are not achieving target glucose control or not adhering sufficiently to their prescribed insulin therapy.
Typically, regardless of whether a diabetic patient uses multiple direct injections (MDIs) or a pump, the diabetic patient takes fasting blood glucose medication (FBGM) upon awakening from sleep, and also tests for glucose in the blood during or after each meal to determine whether a correction dose is required. In addition, the diabetic patient may test for glucose in the blood prior to sleeping to determine whether a correction dose is required, for instance, after eating a snack before sleeping.
To facilitate infusion therapy, there are generally two types of insulin pumps, namely, conventional pumps and patch pumps. Conventional pumps use a disposable component, typically referred to as an infusion set, tubing set or pump set, which conveys the insulin from a reservoir within the pump into the skin of the user. The infusion set includes a pump connector, a length of tubing, and a hub or base from which a cannula, in the form of a hollow metal infusion needle or flexible plastic catheter, extends. The base typically has an adhesive that retains the base on the skin surface during use. The cannula can be inserted onto the skin manually or with the aid of a manual or automatic insertion device. The insertion device may be a separate unit employed by the user.
Another type of insulin pump is a patch pump. Unlike a conventional infusion pump and infusion set combination, a patch pump is an integrated device that combines most or all of the fluidic components in a single housing. Generally, the housing is adhesively attached to an infusion site on the patient's skin, and does not require the use of a separate infusion or tubing set. A patch pump containing insulin adheres to the skin and delivers the insulin over a period of time via an integrated subcutaneous cannula. Some patch pumps may wirelessly communicate with a separate controller device (as in one device sold by Insulet Corporation under the brand name OmniPod®), while others are completely self-contained. Such patch pumps are replaced on a frequent basis, such as every three days, or when the insulin reservoir is exhausted. Otherwise, complications may occur, such as restriction in the cannula or the infusion site.
As patch pumps are designed to be a self-contained unit that is worn by the patient, preferably, the patch pump is small, so that it does not interfere with the activities of the user. Thus, to minimize discomfort to the user, it would be preferable to minimize the overall thickness of the patch pump. However, to minimize the thickness of the patch pump, the size of its constituent parts should be reduced as much as possible.
In current patch pump designs, tubes, such as plastic tubes, are employed as fluid pathways to route fluid flow from one internal component to another. For example, a tube can connect a medicament reservoir with a delivery needle, but the space required to internally house such a tube adds to the overall size of the patch pump. The use of tubes can increase cost and can result in additional complexity during automated device assembly processes. For example, such device assembly includes connecting the tubes, which adds steps to the assembly process. In addition, preventing leaks from such connections can give rise to additional challenges.
Accordingly, a need exists for an improved fluid path design for use in a limited space environment, such as in a patch pump device, which can cost-effectively transport medicament, while minimizing or reducing the overall size and complexity of the device.